Thousands of years ago, a vast trade route called the Silk Road stretched from China all the way to Turkey and into Europe. Now it appears that modern horses are the result of trades and treks on this route.

Cambridge University zoologist Vera Warmuth analyzed DNA from horses in a wide range of locations on the former Silk Road, thousands of miles apart. What she discovered was a remarkable similarity between them — especially along the routes that were a little more temperate with plenty of grass nearby. Horses in locations along difficult and arduous routes didn't reveal the same genetic similarities.

Ancient human trade facilitated population mixing in horses as far as 8000 km apart. Travelling along more arduous Silk Road routes, for instance across the Himalayas and the Tibetan Plateau, was probably more “costly” because less evidence of gene flow was seen in these areas . . . Warmuth found that horses from within the former Soviet Union countries are no more similar to one another than horses from outside this area. In other words this study suggests that these horses are likely a product of ancient and long-term trading along the Silk Road routes rather than a product of recent trading practices.

The horses of contemporary Asia and Russia are likely the descendants of horses that ancient traders bought, or rode on, while wandering thousands of miles on the Silk Road. This is further evidence that humans have (often unwittingly) been guiding the evolution of the animals around them for millennia.